Various types of sensors are used widely in physics, chemistry, and engineering and find use in a wide range of applications, including consumer electronics and medical devices, among others. Some of these sensors use optical signals to sense or measure parameters of interest, e.g., pressure, distance, temperature or composition.
In many applications, it is desirable to provide particularly small sensors. Furthermore, there is generally a demand for particularly precise and sensitive sensors. In designing small optical sensors, for example, issues of electrical interference, optical crosstalk, and signal-to-noise ratio often need to be addressed. There are various potential sources of optical interference in some optical sensors: external (e.g., sunlight, indoor lighting, unintended targets) and internal (e.g., optical crosstalk between the subcomponents of the optical sensor). External interference sometimes can be suppressed or reduced as part of signal processing. Internal interference, on the other hand, can be more challenging to manage, particularly in applications where the sensor is mounted behind a transparent or semi-transparent cover such that the intensity of the light reflected from the cover may be similar in magnitude to the signal of interest.